Undelete: deleted accounts are kept for their period, hold their addresses, and are restored or destroyed through inbuxa:DeletedAccount (UD-15 to UD-17a)

With archiveDeletedAccountsFor set, a destroyed account's record is kept in
the fork subspace with its id, its DestroyAccount task is due at the end of
the period, and its shares are suspended both ways. Its addresses can't be
taken by new accounts, aliases, lists or masks. inbuxa:DeletedAccount/get
lists kept accounts to server and tenant administrators; /set restores one
with a new password (same id, task cancelled, shares reinstated) or destroys
it now. The destroy task also clears undelete's own records.
Acceptance test 14; test 16 written as the ignored undelete_compat.

crates/features/src/undelete/accounts.rs

@@ -0,0 +1,145 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! Deleted accounts kept for their period (UD-15 to UD-17a). The account's
+//! record is removed as upstream removes it; a copy waits here with its
+//! shares, both ways, until it's restored or its `DestroyAccount` task runs.
+
+use crate::undelete::{
+    data::{self, Share},
+    records,
+};
+use store::{
+    Deserialize, IterateParams, RegistryStore, SerializeInfallible, Store, U32_LEN, ValueKey,
+    write::{BatchBuilder, ValueClass, key::DeserializeBigEndian},
+};
+use trc::AddContext;
+use types::collection::Collection;
+
+/// Every share `account_id` is part of, either way.
+async fn shares_of(data: &Store, account_id: u32) -> trc::Result<Vec<Share>> {
+    let mut shares = Vec::new();
+    data.iterate(
+        IterateParams::new(
+            ValueKey {
+                account_id: 0,
+                collection: 0,
+                document_id: 0,
+                class: ValueClass::Acl(0),
+            },
+            ValueKey {
+                account_id: u32::MAX,
+                collection: u8::MAX,
+                document_id: u32::MAX,
+                class: ValueClass::Acl(u32::MAX),
+            },
+        )
+        .ascending(),
+        |key, value| {
+            // grantee, owner, collection, document
+            let grantee = key.deserialize_be_u32(0)?;
+            let owner = key.deserialize_be_u32(U32_LEN)?;
+            if grantee == account_id || owner == account_id {
+                shares.push(Share {
+                    grantee,
+                    owner,
+                    collection: *key.get(U32_LEN * 2).ok_or_else(|| {
+                        trc::StoreEvent::DataCorruption.caused_by(trc::location!())
+                    })?,
+                    document_id: key.deserialize_be_u32(U32_LEN * 2 + 1)?,
+                    permissions: u64::deserialize(value)?,
+                });
+            }
+            Ok(true)
+        },
+    )
+    .await
+    .caused_by(trc::location!())?;
+    Ok(shares)
+}
+
+fn write_shares<'x>(
+    batch: &mut BatchBuilder,
+    shares: impl Iterator<Item = &'x Share>,
+    grant: bool,
+) {
+    for share in shares {
+        batch
+            .with_account_id(share.owner)
+            .with_collection(Collection::from(share.collection))
+            .with_document(share.document_id);
+        if grant {
+            batch.acl_grant(share.grantee, share.permissions.serialize());
+        } else {
+            batch.acl_revoke(share.grantee);
+        }
+    }
+}
+
+/// Revokes every share an account is part of and returns them (UD-17a).
+pub async fn suspend_shares(data: &Store, account_id: u32) -> trc::Result<Vec<Share>> {
+    let shares = shares_of(data, account_id).await?;
+    for chunk in shares.chunks(1000) {
+        let mut batch = BatchBuilder::new();
+        write_shares(&mut batch, chunk.iter(), false);
+        data.write(batch.build_all())
+            .await
+            .caused_by(trc::location!())?;
+    }
+    Ok(shares)
+}
+
+/// Grants back the suspended shares whose other account still exists
+/// (UD-17a). Returns the other accounts, whose access changes.
+pub async fn reinstate_shares(
+    data: &Store,
+    account_id: u32,
+    shares: &[Share],
+    exists: impl Fn(u32) -> bool,
+) -> trc::Result<Vec<u32>> {
+    let shares = shares
+        .iter()
+        .filter(|share| {
+            let other = if share.owner == account_id {
+                share.grantee
+            } else {
+                share.owner
+            };
+            other == account_id || exists(other)
+        })
+        .collect::<Vec<_>>();
+    for chunk in shares.chunks(1000) {
+        let mut batch = BatchBuilder::new();
+        write_shares(&mut batch, chunk.iter().copied(), true);
+        data.write(batch.build_all())
+            .await
+            .caused_by(trc::location!())?;
+    }
+    let mut others = shares
+        .iter()
+        .flat_map(|share| [share.owner, share.grantee])
+        .filter(|id| *id != account_id)
+        .collect::<Vec<_>>();
+    others.sort_unstable();
+    others.dedup();
+    Ok(others)
+}
+
+/// When the account is finally destroyed: its hold, and everything undelete
+/// kept for it, go too.
+pub async fn forget(data: &Store, registry: &RegistryStore, account_id: u32) -> trc::Result<()> {
+    if let Some(kept) = data::kept_account(data, account_id).await? {
+        let mut batch = BatchBuilder::new();
+        data::clear_kept_account(&mut batch, account_id, &kept);
+        data.write(batch.build_all())
+            .await
+            .caused_by(trc::location!())?;
+    }
+    for (id, item) in records::of_account(data, registry, account_id).await? {
+        records::remove(data, registry, id, &item).await?;
+    }
+    data::clear_account(data, account_id).await
+}

crates/features/src/undelete/data.rs

@@ -163,6 +163,22 @@ pub struct KeptAccount {
     pub member_tenant_id: Option<u64>,
     pub deleted_at: u64,
     pub kept_until: u64,
+    /// The id of its `DestroyAccount` task, due at `kept_until`.
+    #[serde(default)]
+    pub task_id: u64,
+    /// Its shares, both ways, suspended while it's kept (UD-17a).
+    #[serde(default)]
+    pub shares: Vec<Share>,
+}
+
+/// One share: `grantee` may reach `owner`'s document with `permissions`.
+#[derive(Debug, Clone, PartialEq, Eq, SerdeSerialize, SerdeDeserialize)]
+pub struct Share {
+    pub grantee: u32,
+    pub owner: u32,
+    pub collection: u8,
+    pub document_id: u32,
+    pub permissions: u64,
 }
 
 pub fn note_email(
@@ -382,6 +398,44 @@ pub async fn kept_accounts(data: &Store) -> trc::Result<Vec<(u32, KeptAccount)>>
     Ok(kept)
 }
 
+/// Clears what's kept under an account's id: its notes, archive links and
+/// change log. The records themselves go with `records::remove`.
+pub async fn clear_account(data: &Store, account_id: u32) -> trc::Result<()> {
+    // Account ids stop short of u32::MAX, the store's sentinel
+    let (from, to) = (account_id.to_be_bytes(), (account_id + 1).to_be_bytes());
+    let mut ranges = vec![
+        (vec![KIND_NOTE], vec![KIND_NOTE]),
+        (vec![KIND_BLOB], vec![KIND_BLOB]),
+        (vec![KIND_CHANGE], vec![KIND_CHANGE]),
+    ];
+    // The groupware notes, `Ug` + kind + account + document
+    for kind in 0u8..3 {
+        ranges.push((vec![b'g', kind], vec![b'g', kind]));
+    }
+    for (mut start, mut end) in ranges {
+        start.extend_from_slice(&from);
+        end.extend_from_slice(&to);
+        data.delete_range(
+            ValueKey::from(class_raw(&start)),
+            ValueKey::from(class_raw(&end)),
+        )
+        .await
+        .caused_by(trc::location!())?;
+    }
+    Ok(())
+}
+
+/// A key under `U` spelled out in full (the groupware notes, `Ug`).
+fn class_raw(rest: &[u8]) -> ValueClass {
+    let mut key = Vec::with_capacity(1 + rest.len());
+    key.push(FEATURE);
+    key.extend_from_slice(rest);
+    ValueClass::Any(AnyClass {
+        subspace: SUBSPACE_INBUXA,
+        key,
+    })
+}
+
 /// The kept account an address is reserved for (UD-16).
 pub async fn reserved_by(data: &Store, address: &str) -> trc::Result<Option<u32>> {
     data.get_value::<u32>(key(KIND_RESERVED, address.to_lowercase().as_bytes()))

crates/features/src/undelete/mod.rs

@@ -13,6 +13,7 @@
 //! beyond them, and the fork's bookkeeping, live in the fork's own subspace
 //! (`data`). Requirements are named `UD-n`, after the spec.
 
+pub mod accounts;
 pub mod data;
 pub mod email;
 pub mod groupware;

crates/jmap-proto/src/object/inbuxa_deleted_account.rs

@@ -0,0 +1,181 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! `inbuxa:DeletedAccount/get` and `/set` under `urn:inbuxa:jmap`: deleted
+//! accounts kept for their period, listed, restored or destroyed for good
+//! (undelete spec, UD-15 to UD-17).
+
+use crate::{
+    object::{AnyId, JmapObject, JmapObjectId},
+    types::date::UTCDate,
+};
+use jmap_tools::{Element, Key, Property};
+use std::{borrow::Cow, str::FromStr};
+use types::id::Id;
+
+#[derive(Debug, Clone, Default)]
+pub struct DeletedAccount;
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum DeletedAccountProperty {
+    Id,
+    Name,
+    Addresses,
+    MemberTenantId,
+    DeletedAt,
+    KeptUntil,
+    Restore,
+    Password,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum DeletedAccountValue {
+    Id(Id),
+    Date(UTCDate),
+}
+
+impl Property for DeletedAccountProperty {
+    fn try_parse(_: Option<&Key<'_, Self>>, value: &str) -> Option<Self> {
+        DeletedAccountProperty::parse(value)
+    }
+
+    fn to_cow(&self) -> Cow<'static, str> {
+        match self {
+            DeletedAccountProperty::Id => "id",
+            DeletedAccountProperty::Name => "name",
+            DeletedAccountProperty::Addresses => "addresses",
+            DeletedAccountProperty::MemberTenantId => "memberTenantId",
+            DeletedAccountProperty::DeletedAt => "deletedAt",
+            DeletedAccountProperty::KeptUntil => "keptUntil",
+            DeletedAccountProperty::Restore => "restore",
+            DeletedAccountProperty::Password => "password",
+        }
+        .into()
+    }
+}
+
+impl DeletedAccountProperty {
+    fn parse(value: &str) -> Option<Self> {
+        hashify::tiny_map!(value.as_bytes(),
+            b"id" => DeletedAccountProperty::Id,
+            b"name" => DeletedAccountProperty::Name,
+            b"addresses" => DeletedAccountProperty::Addresses,
+            b"memberTenantId" => DeletedAccountProperty::MemberTenantId,
+            b"deletedAt" => DeletedAccountProperty::DeletedAt,
+            b"keptUntil" => DeletedAccountProperty::KeptUntil,
+            b"restore" => DeletedAccountProperty::Restore,
+            b"password" => DeletedAccountProperty::Password,
+        )
+    }
+}
+
+impl FromStr for DeletedAccountProperty {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        DeletedAccountProperty::parse(s).ok_or(())
+    }
+}
+
+impl Element for DeletedAccountValue {
+    type Property = DeletedAccountProperty;
+
+    fn try_parse<P>(key: &Key<'_, Self::Property>, value: &str) -> Option<Self> {
+        match key {
+            Key::Property(DeletedAccountProperty::Id | DeletedAccountProperty::MemberTenantId) => {
+                Id::from_str(value).ok().map(DeletedAccountValue::Id)
+            }
+            Key::Property(DeletedAccountProperty::DeletedAt | DeletedAccountProperty::KeptUntil) => {
+                UTCDate::from_str(value).ok().map(DeletedAccountValue::Date)
+            }
+            _ => None,
+        }
+    }
+
+    fn to_cow(&self) -> Cow<'static, str> {
+        match self {
+            DeletedAccountValue::Id(id) => id.to_string().into(),
+            DeletedAccountValue::Date(date) => date.to_string().into(),
+        }
+    }
+}
+
+impl JmapObject for DeletedAccount {
+    type Property = DeletedAccountProperty;
+
+    type Element = DeletedAccountValue;
+
+    type Id = Id;
+
+    type Filter = ();
+
+    type Comparator = ();
+
+    type GetArguments = ();
+
+    type SetArguments<'de> = ();
+
+    type QueryArguments = ();
+
+    type CopyArguments = ();
+
+    type ParseArguments = ();
+
+    const ID_PROPERTY: Self::Property = DeletedAccountProperty::Id;
+}
+
+impl From<Id> for DeletedAccountValue {
+    fn from(id: Id) -> Self {
+        DeletedAccountValue::Id(id)
+    }
+}
+
+impl JmapObjectId for DeletedAccountValue {
+    fn as_id(&self) -> Option<Id> {
+        match self {
+            DeletedAccountValue::Id(id) => Some(*id),
+            _ => None,
+        }
+    }
+
+    fn as_any_id(&self) -> Option<AnyId> {
+        match self {
+            DeletedAccountValue::Id(id) => Some(AnyId::Id(*id)),
+            _ => None,
+        }
+    }
+
+    fn as_id_ref(&self) -> Option<&str> {
+        None
+    }
+
+    fn try_set_id(&mut self, new_id: AnyId) -> bool {
+        if let AnyId::Id(id) = new_id {
+            *self = DeletedAccountValue::Id(id);
+            true
+        } else {
+            false
+        }
+    }
+}
+
+impl JmapObjectId for DeletedAccountProperty {
+    fn as_id(&self) -> Option<Id> {
+        None
+    }
+
+    fn as_any_id(&self) -> Option<AnyId> {
+        None
+    }
+
+    fn as_id_ref(&self) -> Option<&str> {
+        None
+    }
+
+    fn try_set_id(&mut self, _: AnyId) -> bool {
+        false
+    }
+}

crates/jmap-proto/src/object/mod.rs

@@ -19,6 +19,7 @@ pub mod contact;
 pub mod email;
 pub mod email_submission;
 pub mod fastmail_masked_email; // inbuxa: masked email
+pub mod inbuxa_deleted_account; // inbuxa: undelete
 pub mod file_node;
 pub mod identity;
 pub mod mailbox;

crates/jmap-proto/src/references/eval.rs

@@ -53,6 +53,9 @@ impl Response<'_> {
                         GetResponseMethod::MaskedEmail(response) => {
                             response.eval_jptr(path, &mut results)
                         }
+                        GetResponseMethod::DeletedAccount(response) => {
+                            response.eval_jptr(path, &mut results)
+                        }
                         GetResponseMethod::Principal(response) => {
                             response.eval_jptr(path, &mut results)
                         }

crates/jmap-proto/src/references/resolve.rs

@@ -42,6 +42,7 @@ impl Response<'_> {
                 GetRequestMethod::Sieve(request) => request.resolve_references(self)?,
                 GetRequestMethod::VacationResponse(request) => request.resolve_references(self)?,
                 GetRequestMethod::MaskedEmail(request) => request.resolve_references(self)?,
+                GetRequestMethod::DeletedAccount(request) => request.resolve_references(self)?,
                 GetRequestMethod::Principal(request) => request.resolve_references(self)?,
                 GetRequestMethod::Quota(request) => request.resolve_references(self)?,
                 GetRequestMethod::Blob(request) => request.resolve_references(self)?,
@@ -79,6 +80,9 @@ impl Response<'_> {
                 SetRequestMethod::MaskedEmail(request) => {
                     request.resolve_references(self, 1, false)?
                 }
+                SetRequestMethod::DeletedAccount(request) => {
+                    request.resolve_references(self, 1, false)?
+                }
                 SetRequestMethod::AddressBook(request) => {
                     request.resolve_references(self, 1, false)?
                 }

crates/jmap-proto/src/request/method.rs

@@ -43,6 +43,8 @@ pub enum MethodObject {
     Registry(ObjectType),
     // inbuxa: Fastmail's MaskedEmail
     MaskedEmail,
+    // inbuxa: deleted accounts (UD-17)
+    DeletedAccount,
 }
 
 impl MethodObject {
@@ -67,6 +69,7 @@ impl MethodObject {
             MethodObject::FileNode => Capability::FileNode,
             MethodObject::Registry(_) => Capability::Stalwart,
             MethodObject::MaskedEmail => Capability::FastmailMaskedEmail,
+            MethodObject::DeletedAccount => Capability::Inbuxa,
         }
     }
 }
@@ -240,6 +243,8 @@ impl MethodName {
             (MethodFunction::Echo, MethodObject::Core) => "Core/echo",
             (MethodFunction::Get, MethodObject::MaskedEmail) => "MaskedEmail/get",
             (MethodFunction::Set, MethodObject::MaskedEmail) => "MaskedEmail/set",
+            (MethodFunction::Get, MethodObject::DeletedAccount) => "inbuxa:DeletedAccount/get",
+            (MethodFunction::Set, MethodObject::DeletedAccount) => "inbuxa:DeletedAccount/set",
             (method, MethodObject::Registry(obj)) => {
                 return Cow::Owned(format!("x:{}/{}", obj.as_str(), method.as_str()));
             }
@@ -361,6 +366,8 @@ impl MethodName {
 
             "MaskedEmail/get" => (MethodObject::MaskedEmail, MethodFunction::Get),
             "MaskedEmail/set" => (MethodObject::MaskedEmail, MethodFunction::Set),
+            "inbuxa:DeletedAccount/get" => (MethodObject::DeletedAccount, MethodFunction::Get),
+            "inbuxa:DeletedAccount/set" => (MethodObject::DeletedAccount, MethodFunction::Set),
 
         ).or_else(|| {
             let (obj, fnc) = s.strip_prefix("x:")?.split_once('/')?;
@@ -412,6 +419,7 @@ impl Display for MethodObject {
             MethodObject::CalendarEventNotification => "CalendarEventNotification",
             MethodObject::ShareNotification => "ShareNotification",
             MethodObject::MaskedEmail => "MaskedEmail",
+            MethodObject::DeletedAccount => "inbuxa:DeletedAccount",
             MethodObject::Registry(obj) => {
                 f.write_str("x:")?;
                 return f.write_str(obj.as_str());

crates/jmap-proto/src/request/mod.rs

@@ -112,6 +112,7 @@ pub enum GetRequestMethod {
     ShareNotification(Box<GetRequest<ShareNotification>>),
     Registry(Box<GetRequest<Registry>>),
     MaskedEmail(Box<GetRequest<crate::object::fastmail_masked_email::FastmailMaskedEmail>>),
+    DeletedAccount(Box<GetRequest<crate::object::inbuxa_deleted_account::DeletedAccount>>),
 }
 
 #[derive(Debug)]
@@ -133,6 +134,7 @@ pub enum SetRequestMethod<'x> {
     ParticipantIdentity(Box<SetRequest<'x, ParticipantIdentity>>),
     Registry(Box<SetRequest<'x, Registry>>),
     MaskedEmail(Box<SetRequest<'x, crate::object::fastmail_masked_email::FastmailMaskedEmail>>),
+    DeletedAccount(Box<SetRequest<'x, crate::object::inbuxa_deleted_account::DeletedAccount>>),
 }
 
 #[derive(Debug)]

crates/jmap-proto/src/request/parser.rs

@@ -153,6 +153,13 @@ impl<'de> Visitor<'de> for CallVisitor {
                     return Err(de::Error::invalid_length(1, &self));
                 }
             },
+            (MethodFunction::Get, MethodObject::DeletedAccount) => match seq.next_element() {
+                Ok(Some(value)) => RequestMethod::Get(GetRequestMethod::DeletedAccount(value)),
+                Err(err) => RequestMethod::invalid(err),
+                Ok(None) => {
+                    return Err(de::Error::invalid_length(1, &self));
+                }
+            },
             (MethodFunction::Get, MethodObject::VacationResponse) => match seq.next_element() {
                 Ok(Some(value)) => RequestMethod::Get(GetRequestMethod::VacationResponse(value)),
                 Err(err) => RequestMethod::invalid(err),
@@ -304,6 +311,13 @@ impl<'de> Visitor<'de> for CallVisitor {
                     return Err(de::Error::invalid_length(1, &self));
                 }
             },
+            (MethodFunction::Set, MethodObject::DeletedAccount) => match seq.next_element() {
+                Ok(Some(value)) => RequestMethod::Set(SetRequestMethod::DeletedAccount(value)),
+                Err(err) => RequestMethod::invalid(err),
+                Ok(None) => {
+                    return Err(de::Error::invalid_length(1, &self));
+                }
+            },
             (MethodFunction::Set, MethodObject::VacationResponse) => match seq.next_element() {
                 Ok(Some(value)) => RequestMethod::Set(SetRequestMethod::VacationResponse(value)),
                 Err(err) => RequestMethod::invalid(err),

crates/jmap-proto/src/response/mod.rs

@@ -99,6 +99,7 @@ pub enum GetResponseMethod {
     ShareNotification(GetResponse<ShareNotification>),
     Registry(GetResponse<Registry>),
     MaskedEmail(GetResponse<crate::object::fastmail_masked_email::FastmailMaskedEmail>),
+    DeletedAccount(GetResponse<crate::object::inbuxa_deleted_account::DeletedAccount>),
 }
 
 #[derive(Debug, serde::Serialize)]
@@ -121,6 +122,7 @@ pub enum SetResponseMethod {
     ParticipantIdentity(Box<SetResponse<ParticipantIdentity>>),
     Registry(Box<SetResponse<Registry>>),
     MaskedEmail(Box<SetResponse<crate::object::fastmail_masked_email::FastmailMaskedEmail>>),
+    DeletedAccount(Box<SetResponse<crate::object::inbuxa_deleted_account::DeletedAccount>>),
 }
 
 #[derive(Debug, serde::Serialize)]
@@ -280,6 +282,19 @@ impl<'x> From<SetResponse<crate::object::fastmail_masked_email::FastmailMaskedEm
     }
 }
 
+// inbuxa: deleted accounts (UD-17)
+impl<'x> From<GetResponse<crate::object::inbuxa_deleted_account::DeletedAccount>> for ResponseMethod<'x> {
+    fn from(value: GetResponse<crate::object::inbuxa_deleted_account::DeletedAccount>) -> Self {
+        ResponseMethod::Get(GetResponseMethod::DeletedAccount(value))
+    }
+}
+
+impl<'x> From<SetResponse<crate::object::inbuxa_deleted_account::DeletedAccount>> for ResponseMethod<'x> {
+    fn from(value: SetResponse<crate::object::inbuxa_deleted_account::DeletedAccount>) -> Self {
+        ResponseMethod::Set(SetResponseMethod::DeletedAccount(Box::new(value)))
+    }
+}
+
 impl<'x> From<GetResponse<VacationResponse>> for ResponseMethod<'x> {
     fn from(value: GetResponse<VacationResponse>) -> Self {
         ResponseMethod::Get(GetResponseMethod::VacationResponse(value))

crates/jmap/src/api/auth.rs

@@ -71,6 +71,8 @@ impl JmapAuthorization for AccessToken {
                 GetRequestMethod::VacationResponse(_) => Permission::JmapVacationResponseGet,
                 // inbuxa: Fastmail's MaskedEmail (ME-18)
                 GetRequestMethod::MaskedEmail(_) => Permission::SysMaskedEmailGet,
+                // inbuxa: deleted accounts (UD-17)
+                GetRequestMethod::DeletedAccount(_) => Permission::SysAccountGet,
                 GetRequestMethod::Principal(_) => Permission::JmapPrincipalGet,
                 GetRequestMethod::Quota(_) => Permission::JmapQuotaGet,
                 GetRequestMethod::Blob(_) => Permission::JmapBlobGet,
@@ -151,6 +153,14 @@ impl JmapAuthorization for AccessToken {
                         Permission::SysMaskedEmailUpdate,
                         Permission::SysMaskedEmailDestroy,
                     ),
+                    // inbuxa: deleted accounts; a restore creates the account again (UD-17)
+                    SetRequestMethod::DeletedAccount(s) => validate_set(
+                        s,
+                        self,
+                        Permission::SysAccountCreate,
+                        Permission::SysAccountCreate,
+                        Permission::SysAccountDestroy,
+                    ),
                     SetRequestMethod::VacationResponse(s) => validate_set(
                         s,
                         self,
@@ -258,7 +268,8 @@ impl JmapAuthorization for AccessToken {
                 | MethodObject::SearchSnippet
                 | MethodObject::VacationResponse
                 | MethodObject::SieveScript
-                | MethodObject::MaskedEmail => Permission::JmapEmailChanges,
+                | MethodObject::MaskedEmail
+                | MethodObject::DeletedAccount => Permission::JmapEmailChanges,
                 // inbuxa: x:MaskedEmail/changes reads what /get reads
                 MethodObject::Registry(object_type) => object_type.get_permission(),
             },

crates/jmap/src/api/request.rs

@@ -165,6 +165,9 @@ impl RequestHandler for Server {
                                     SetResponseMethod::MaskedEmail(set_response) => {
                                         set_response.update_created_ids(&mut response);
                                     }
+                                    SetResponseMethod::DeletedAccount(set_response) => {
+                                        set_response.update_created_ids(&mut response);
+                                    }
                                     SetResponseMethod::AddressBook(set_response) => {
                                         set_response.update_created_ids(&mut response);
                                     }
@@ -306,6 +309,13 @@ impl RequestHandler for Server {
                         .await?
                         .into()
                 }
+                // inbuxa: inbuxa:DeletedAccount/get (UD-17)
+                GetRequestMethod::DeletedAccount(mut req) => {
+                    resolve_account_id(&mut req.account_id, method_name.obj, access_token)?;
+                    crate::inbuxa::deleted_account::get(self, access_token, *req)
+                        .await?
+                        .into()
+                }
                 GetRequestMethod::Principal(req) => {
                     self.principal_get(*req, access_token).await?.into()
                 }
@@ -533,6 +543,13 @@ impl RequestHandler for Server {
                         .await?
                         .into()
                 }
+                // inbuxa: inbuxa:DeletedAccount/set (UD-17)
+                SetRequestMethod::DeletedAccount(mut req) => {
+                    resolve_account_id(&mut req.account_id, method_name.obj, access_token)?;
+                    crate::inbuxa::deleted_account::set(self, access_token, *req)
+                        .await?
+                        .into()
+                }
                 SetRequestMethod::AddressBook(mut req) => {
                     resolve_account_id(&mut req.account_id, method_name.obj, access_token)?;
                     access_token.assert_has_access(req.account_id, Collection::AddressBook)?;

crates/jmap/src/changes/get.rs

@@ -414,6 +414,7 @@ impl IntermediateChangesResponse {
             | MethodObject::Principal
             | MethodObject::Quota
             | MethodObject::MaskedEmail
+            | MethodObject::DeletedAccount
             | MethodObject::Registry(_) => unreachable!(),
         })
     }

crates/jmap/src/inbuxa/deleted_account.rs

@@ -0,0 +1,529 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! Deleted accounts kept for their period (undelete spec, UD-15 to UD-17a):
+//! kept at deletion, their addresses held, and listed, restored or
+//! destroyed for good through `inbuxa:DeletedAccount/get` and `/set`.
+
+use common::{
+    Server,
+    auth::AccessToken,
+    cache::invalidate::CacheInvalidationBuilder,
+    ipc::CacheInvalidation,
+};
+use directory::core::secret::hash_secret;
+use inbuxa_features::undelete::{
+    accounts,
+    data::{self, KeptAccount},
+    settings::retention,
+};
+use jmap_proto::{
+    error::set::{SetError, SetErrorType},
+    method::{
+        get::{GetRequest, GetResponse},
+        set::{SetRequest, SetResponse},
+    },
+    object::inbuxa_deleted_account::{
+        DeletedAccount, DeletedAccountProperty as P, DeletedAccountValue,
+    },
+    request::IntoValid,
+    types::date::UTCDate,
+};
+use jmap_tools::{Key, Map, Value};
+use registry::{
+    pickle::PickledStream,
+    schema::{
+        enums::{AccountType, Permission},
+        prelude::{Object, ObjectInner, ObjectType, Property},
+        structs::{Account, Credential, Task, TaskDestroyAccount, TaskStatus},
+    },
+    types::{EnumImpl, datetime::UTCDateTime, id::ObjectId},
+};
+use std::borrow::Cow;
+use store::{
+    registry::write::{RegistryWrite, RegistryWriteResult},
+    write::{BatchBuilder, TaskQueueClass, ValueClass, now},
+};
+use trc::AddContext;
+use types::id::Id;
+use utils::snowflake::SnowflakeIdGenerator;
+
+type DValue = Value<'static, P, DeletedAccountValue>;
+
+const ALL: &[P] = &[
+    P::Id,
+    P::Name,
+    P::Addresses,
+    P::MemberTenantId,
+    P::DeletedAt,
+    P::KeptUntil,
+];
+
+/// The addresses an object answers to, with the property that names each.
+async fn addresses_of(server: &Server, inner: &ObjectInner) -> trc::Result<Vec<(Property, String)>> {
+    let (name, domain_id, aliases) = match inner {
+        ObjectInner::Account(Account::User(account)) => {
+            (&account.name, account.domain_id, &account.aliases)
+        }
+        ObjectInner::Account(Account::Group(account)) => {
+            (&account.name, account.domain_id, &account.aliases)
+        }
+        ObjectInner::MailingList(list) => (&list.name, list.domain_id, &list.aliases),
+        ObjectInner::MaskedEmail(mask) => {
+            return Ok(vec![(Property::Email, mask.email.to_lowercase())]);
+        }
+        _ => return Ok(vec![]),
+    };
+    let mut addresses = Vec::new();
+    for (property, local, domain_id) in std::iter::once((Property::Name, name, domain_id)).chain(
+        aliases
+            .values()
+            .map(|alias| (Property::Aliases, &alias.name, alias.domain_id)),
+    ) {
+        if let Some(domain) = server.domain_by_id(domain_id.document_id()).await? {
+            for domain in domain.names.iter() {
+                addresses.push((property, format!("{local}@{domain}").to_lowercase()));
+            }
+        }
+    }
+    Ok(addresses)
+}
+
+/// UD-16: nothing new may take an address a kept account holds.
+pub async fn reserved(
+    server: &Server,
+    old: Option<&Object>,
+    new: &Object,
+) -> trc::Result<Option<SetError<Property>>> {
+    let before = match old {
+        Some(old) => addresses_of(server, &old.inner).await?,
+        None => vec![],
+    };
+    for (property, address) in addresses_of(server, &new.inner).await? {
+        if before.iter().any(|(_, a)| *a == address) {
+            continue;
+        }
+        if let Some(kept_id) = data::reserved_by(&server.core.storage.data, &address).await? {
+            return Ok(Some(
+                SetError::new(SetErrorType::PrimaryKeyViolation)
+                    .with_property(property)
+                    .with_object_id(ObjectId::new(ObjectType::Account, Id::from(kept_id)))
+                    .with_description(format!(
+                        "{address} is held by a deleted account until it's destroyed."
+                    )),
+            ));
+        }
+    }
+    Ok(None)
+}
+
+/// UD-15: keeps a destroyed account for the period, if one is set, instead
+/// of upstream's immediate destruction. Returns the other accounts whose
+/// access changed, or `None` when nothing is kept.
+pub async fn keep(server: &Server, id: Id, account: &Account) -> trc::Result<Option<Vec<u32>>> {
+    let Some(period) = retention(server.registry()).await?.accounts else {
+        return Ok(None);
+    };
+    let account_id = id.document_id();
+    let deleted_at = now();
+    let kept_until = deleted_at + period;
+    let inner = ObjectInner::Account(account.clone());
+    let addresses = addresses_of(server, &inner)
+        .await?
+        .into_iter()
+        .map(|(_, address)| address)
+        .collect();
+    let (domain_id, name, account_type, tenant) = match account {
+        Account::User(a) => (a.domain_id, a.name.clone(), AccountType::User, a.member_tenant_id),
+        Account::Group(a) => (a.domain_id, a.name.clone(), AccountType::Group, a.member_tenant_id),
+    };
+
+    // UD-17a: its shares are suspended both ways
+    let data = &server.core.storage.data;
+    let shares = accounts::suspend_shares(data, account_id).await?;
+    let mut others = shares
+        .iter()
+        .flat_map(|share| [share.owner, share.grantee])
+        .filter(|other| *other != account_id)
+        .collect::<Vec<_>>();
+    others.sort_unstable();
+    others.dedup();
+
+    // UD-15a: upstream's DestroyAccount task, due at the end of the period
+    let task_id = SnowflakeIdGenerator::global_id().unwrap_or_default();
+    let kept = KeptAccount {
+        record: inner.to_pickled_vec(),
+        name: name.clone(),
+        addresses,
+        member_tenant_id: tenant.map(|id| id.id()),
+        deleted_at,
+        kept_until,
+        task_id,
+        shares,
+    };
+    let mut batch = BatchBuilder::new();
+    batch.schedule_task_with_id(
+        task_id,
+        Task::DestroyAccount(TaskDestroyAccount {
+            account_domain_id: domain_id,
+            account_id: id,
+            account_name: name,
+            account_type,
+            status: TaskStatus::at(kept_until as i64),
+        }),
+    );
+    data::set_kept_account(&mut batch, account_id, &kept)?;
+    data.write(batch.build_all())
+        .await
+        .caused_by(trc::location!())?;
+    server.notify_task_queue();
+    Ok(Some(others))
+}
+
+/// Who may see or act on a kept account: server administrators, and tenant
+/// administrators for their own tenant's (MT-1).
+fn may_reach(access_token: &AccessToken, kept: &KeptAccount, permission: Permission) -> bool {
+    access_token.has_permission(permission)
+        && access_token
+            .tenant_id()
+            .is_none_or(|tenant| kept.member_tenant_id == Some(tenant as u64))
+}
+
+fn date(timestamp: u64) -> DValue {
+    Value::Element(DeletedAccountValue::Date(UTCDate::from_timestamp(
+        timestamp as i64,
+    )))
+}
+
+fn to_value(account_id: u32, kept: &KeptAccount, properties: &[P]) -> DValue {
+    let mut out = Map::with_capacity(properties.len());
+    for property in properties {
+        let value = match property {
+            P::Id => Value::Element(DeletedAccountValue::Id(Id::from(account_id))),
+            P::Name => Value::Str(Cow::Owned(kept.name.clone())),
+            P::Addresses => Value::Array(
+                kept.addresses
+                    .iter()
+                    .map(|a| Value::Str(Cow::Owned(a.clone())))
+                    .collect(),
+            ),
+            P::MemberTenantId => match kept.member_tenant_id {
+                Some(id) => Value::Element(DeletedAccountValue::Id(Id::from(id))),
+                None => Value::Null,
+            },
+            P::DeletedAt => date(kept.deleted_at),
+            P::KeptUntil => date(kept.kept_until),
+            P::Restore | P::Password => continue,
+        };
+        out.insert_unchecked(Key::Property(property.clone()), value);
+    }
+    Value::Object(out)
+}
+
+/// `inbuxa:DeletedAccount/get`.
+pub async fn get(
+    server: &Server,
+    access_token: &AccessToken,
+    mut request: GetRequest<DeletedAccount>,
+) -> trc::Result<GetResponse<DeletedAccount>> {
+    let properties = request.unwrap_properties(ALL);
+    let (ids, not_found) = request.unwrap_ids(server.core.jmap.get_max_objects)?;
+    let mut response = GetResponse {
+        account_id: request.account_id.into(),
+        state: None,
+        list: Vec::new(),
+        not_found,
+    };
+    let data = &server.core.storage.data;
+    match ids {
+        None => {
+            for (account_id, kept) in data::kept_accounts(data).await? {
+                if may_reach(access_token, &kept, Permission::SysAccountGet) {
+                    response.list.push(to_value(account_id, &kept, &properties));
+                }
+            }
+        }
+        Some(ids) => {
+            for id in ids {
+                match data::kept_account(data, id.document_id()).await? {
+                    Some(kept) if may_reach(access_token, &kept, Permission::SysAccountGet) => {
+                        response
+                            .list
+                            .push(to_value(id.document_id(), &kept, &properties));
+                    }
+                    _ => response.push_not_found(id),
+                }
+            }
+        }
+    }
+    Ok(response)
+}
+
+/// `inbuxa:DeletedAccount/set`: update `{"restore": true, "password": ...}`
+/// restores; destroy destroys for good.
+pub async fn set(
+    server: &Server,
+    access_token: &AccessToken,
+    mut request: SetRequest<'_, DeletedAccount>,
+) -> trc::Result<SetResponse<DeletedAccount>> {
+    let mut response = SetResponse::from_request(&request, server.core.jmap.set_max_objects)?;
+    let will_destroy = request.unwrap_destroy().into_valid().collect::<Vec<_>>();
+    let data = &server.core.storage.data;
+
+    for (client_id, _) in request.unwrap_create() {
+        response.not_created.append(
+            client_id,
+            SetError::forbidden().with_description("Only a deleted account can be restored."),
+        );
+    }
+
+    for (id, value) in request.unwrap_update().into_valid() {
+        let kept = match data::kept_account(data, id.document_id()).await? {
+            Some(kept) if may_reach(access_token, &kept, Permission::SysAccountCreate) => kept,
+            _ => {
+                response.not_updated.append(id, SetError::not_found());
+                continue;
+            }
+        };
+        let (mut restore, mut password) = (false, None);
+        let mut invalid = None;
+        for (key, value) in value.into_expanded_object() {
+            match (&key, value) {
+                (Key::Property(P::Restore), Value::Bool(value)) => restore = value,
+                (Key::Property(P::Password), Value::Str(value)) => password = Some(value.into_owned()),
+                (Key::Property(P::Password), Value::Null) => password = None,
+                _ => invalid = Some(key.into_owned()),
+            }
+        }
+        if let Some(key) = invalid {
+            response.not_updated.append(
+                id,
+                SetError::invalid_properties()
+                    .with_property(key)
+                    .with_description("Only restore and password can be set."),
+            );
+            continue;
+        }
+        if !restore {
+            response.not_updated.append(
+                id,
+                SetError::invalid_properties()
+                    .with_property(P::Restore)
+                    .with_description("Set restore to true to restore the account."),
+            );
+            continue;
+        }
+        match restore_account(server, access_token, id, kept, password).await? {
+            Ok(()) => response.updated.append(id, None),
+            Err(err) => response.not_updated.append(id, err),
+        }
+    }
+
+    for id in will_destroy {
+        match data::kept_account(data, id.document_id()).await? {
+            Some(kept) if may_reach(access_token, &kept, Permission::SysAccountDestroy) => {
+                destroy_now(server, id, &kept).await?;
+                response.destroyed.push(id);
+            }
+            _ => response.not_destroyed.append(id, SetError::not_found()),
+        }
+    }
+
+    Ok(response)
+}
+
+fn failed(err: SetError<Property>) -> SetError<P> {
+    let mut out = SetError::new(err.error_type().clone());
+    if let Some(description) = err.description() {
+        out = out.with_description(description.to_string());
+    }
+    out
+}
+
+/// UD-17: writes the record back with the same id and a new password,
+/// cancels the pending destruction and reinstates its shares (UD-17a).
+async fn restore_account(
+    server: &Server,
+    access_token: &AccessToken,
+    id: Id,
+    kept: KeptAccount,
+    password: Option<String>,
+) -> trc::Result<Result<(), SetError<P>>> {
+    let account_id = id.document_id();
+    let Some(ObjectInner::Account(mut account)) = PickledStream::new(&kept.record)
+        .and_then(|mut stream| ObjectInner::unpickle(ObjectType::Account, &mut stream))
+    else {
+        return Ok(Err(SetError::forbidden().with_description("The kept record can't be read.")));
+    };
+
+    // A user comes back with a new password; its other credentials stay
+    if let Account::User(user) = &mut account {
+        let Some(password) = password else {
+            return Ok(Err(SetError::invalid_properties()
+                .with_property(P::Password)
+                .with_description("A restored account needs a new password.")));
+        };
+        if let Err(err) = server.is_secure_password(&password, &[]) {
+            return Ok(Err(SetError::invalid_properties()
+                .with_property(P::Password)
+                .with_description(err)));
+        }
+        let secret = hash_secret(
+            server.core.network.security.password_hash_algorithm,
+            password.into_bytes(),
+        )
+        .await
+        .caused_by(trc::location!())?;
+        let expires_at = server
+            .core
+            .network
+            .security
+            .password_default_expiration
+            .map(|expires| UTCDateTime::from_timestamp((now() + expires) as i64));
+        match user
+            .credentials
+            .values_mut()
+            .find_map(|credential| match credential {
+                Credential::Password(credential) => Some(credential),
+                _ => None,
+            }) {
+            Some(credential) => {
+                credential.secret = secret;
+                credential.expires_at = expires_at;
+            }
+            None => {
+                return Ok(Err(SetError::forbidden()
+                    .with_description("The kept account has no password credential.")));
+            }
+        }
+    }
+
+    // The restorer may only bring back what it could grant
+    if server.can_set_permissions(access_token, &account).await?.is_err() {
+        return Ok(Err(SetError::forbidden().with_description(
+            "You can't grant the permissions this account holds.",
+        )));
+    }
+
+    let object = Object {
+        inner: ObjectInner::Account(account),
+        revision: 0,
+    };
+    if let Err(err) =
+        inbuxa_features::tenancy::writes::check(server.registry(), None, None, &object).await?
+    {
+        return Ok(Err(failed(err)));
+    }
+
+    // Its addresses are free for it alone
+    let mut batch = BatchBuilder::new();
+    data::clear_kept_account(&mut batch, account_id, &kept);
+    let data = &server.core.storage.data;
+    data.write(batch.build_all())
+        .await
+        .caused_by(trc::location!())?;
+
+    match server
+        .registry()
+        .write(RegistryWrite::Insert {
+            object: &object,
+            id: Some(id),
+        })
+        .await?
+    {
+        RegistryWriteResult::Success(_) => {}
+        err => {
+            // Put the hold back
+            let mut batch = BatchBuilder::new();
+            data::set_kept_account(&mut batch, account_id, &kept)?;
+            data.write(batch.build_all())
+                .await
+                .caused_by(trc::location!())?;
+            return Ok(Err(match err {
+                RegistryWriteResult::PrimaryKeyConflict { property, .. } => {
+                    SetError::new(SetErrorType::PrimaryKeyViolation).with_description(format!(
+                        "Another object now has this account's {}.",
+                        property.as_str()
+                    ))
+                }
+                RegistryWriteResult::InvalidForeignKey { object_id } => {
+                    SetError::new(SetErrorType::InvalidForeignKey).with_description(format!(
+                        "{} {} no longer exists.",
+                        object_id.object().as_str(),
+                        object_id.id()
+                    ))
+                }
+                _ => SetError::forbidden().with_description("The account can't be restored."),
+            }));
+        }
+    }
+
+    // Its destruction is off
+    let mut batch = BatchBuilder::new();
+    batch
+        .clear(ValueClass::TaskQueue(TaskQueueClass::Task { id: kept.task_id }))
+        .clear(ValueClass::TaskQueue(TaskQueueClass::Due {
+            id: kept.task_id,
+            due: kept.kept_until,
+        }));
+    data.write(batch.build_all())
+        .await
+        .caused_by(trc::location!())?;
+
+    // UD-17a: its shares come back where the other account still exists
+    let mut existing = Vec::new();
+    for share in &kept.shares {
+        for other in [share.owner, share.grantee] {
+            if other != account_id
+                && !existing.contains(&other)
+                && server
+                    .registry()
+                    .object::<Account>(Id::from(other))
+                    .await?
+                    .is_some()
+            {
+                existing.push(other);
+            }
+        }
+    }
+    let others =
+        accounts::reinstate_shares(data, account_id, &kept.shares, |id| existing.contains(&id))
+            .await?;
+
+    let mut invalidator = CacheInvalidationBuilder::default();
+    invalidator.process_create(&object);
+    invalidator.invalidate(CacheInvalidation::AccessToken(account_id));
+    for other in others {
+        invalidator.invalidate(CacheInvalidation::AccessToken(other));
+    }
+    server.invalidate_caches(invalidator).await?;
+    Ok(Ok(()))
+}
+
+/// Destroys a kept account for good: its `DestroyAccount` task runs now.
+async fn destroy_now(server: &Server, id: Id, kept: &KeptAccount) -> trc::Result<()> {
+    let data = &server.core.storage.data;
+    let task_key = ValueClass::TaskQueue(TaskQueueClass::Task { id: kept.task_id });
+    let mut batch = BatchBuilder::new();
+    if let Some(mut task) = data
+        .get_value::<Task>(store::ValueKey::from(task_key))
+        .await?
+    {
+        task.set_status(TaskStatus::now());
+        batch
+            .clear(ValueClass::TaskQueue(TaskQueueClass::Due {
+                id: kept.task_id,
+                due: kept.kept_until,
+            }))
+            .schedule_task_with_id(kept.task_id, task);
+    }
+    data::clear_kept_account(&mut batch, id.document_id(), kept);
+    data.write(batch.build_all())
+        .await
+        .caused_by(trc::location!())?;
+    server.notify_task_queue();
+    Ok(())
+}

crates/jmap/src/inbuxa/mod.rs

@@ -8,6 +8,7 @@
 //! `crates/features`; this module only speaks JMAP for them.
 
 pub mod access;
+pub mod deleted_account;
 pub mod fastmail;
 pub mod masked_email;
 pub mod undelete;

crates/jmap/src/registry/set.rs

@@ -572,6 +572,14 @@ impl RegistrySet for Server {
                         }
                     };
 
+                    // inbuxa: UD-16: a kept account's addresses stay its own
+                    if let Some(err) =
+                        crate::inbuxa::deleted_account::reserved(self, stored, &new_object).await?
+                    {
+                        set.failed(modification, err);
+                        continue 'outer;
+                    }
+
                     // Validate expressions
                     if let Some(expressions) = new_object.inner.expression_ctxs() {
                         let mut bp = Bootstrap::new_uninitialized(self.registry().clone());
@@ -750,7 +758,17 @@ impl RegistrySet for Server {
                             .await?
                         {
                             RegistryWriteResult::Success(_) => {
-                                if let ObjectInner::Account(account) = &object.inner {
+                                // inbuxa: UD-15, UD-17a: kept for its period, shares suspended
+                                if let ObjectInner::Account(account) = &object.inner
+                                    && let Some(others) =
+                                        crate::inbuxa::deleted_account::keep(self, id, account)
+                                            .await?
+                                {
+                                    for other in others {
+                                        cache_invalidator
+                                            .invalidate(CacheInvalidation::AccessToken(other));
+                                    }
+                                } else if let ObjectInner::Account(account) = &object.inner {
                                     for sharee_id in self
                                         .store()
                                         .acl_revoke_all(id.document_id())
@@ -837,6 +855,7 @@ impl RegistrySet for Server {
                 Ok(set.into_response())
             }
             #[cfg(not(feature = "enterprise"))]
+            #[allow(unreachable_patterns)] // inbuxa: ArchivedItem was the last one
             _ => {
                 set.fail_all_create("Enterprise objects cannot be created");
                 set.fail_all_update("Enterprise objects cannot be modified");

crates/services/src/task_manager/destroy_account.rs

@@ -91,6 +91,14 @@ async fn destroy_account(server: &Server, task: &TaskDestroyAccount) -> trc::Res
         }
     }
 
+    // inbuxa: UD-15: the account's hold and undelete's own records go first
+    inbuxa_features::undelete::accounts::forget(
+        &server.core.storage.data,
+        server.registry(),
+        account_id,
+    )
+    .await?;
+
     // Remove archived items
     let mut batch = BatchBuilder::new();
     let ids = server